April 15, 20197 yr OK, I ticked off another Facebook installer/advertiser. So just to calibrate myself, what say you guys of this kind of PV-module mounting? The installer didn't like it that I asked about the clamp zones. Then there is this quality battery cable job... It seems a bit thin to me... and this 5KVA install which is completely under-batteried... All photos publicly available on Facebook. No names mentioned for obvious reasons. Am I being overly pedantic?
April 15, 20197 yr 13 minutes ago, plonkster said: Am I being overly pedantic? I don't think so. Did you also point out the uncovered battery terminals and using the same conduit for AC and DC? Although I think SA is to paranoid about the separate conduit requirements for AC and DC if the fusing and insulation resistance aspects of the wires are correctly addressed.
April 15, 20197 yr 9 hours ago, Fuenkli said: ... uncovered battery terminals ... Won't get a CoC from my sparkie.
April 16, 20197 yr It look neat and tidy off the bat, yes it has issues but from the cosmetic side the customer is probably quite happy. Until things go wrong. Let's face it most people won't know better unless someone else shows them the light.
April 17, 20197 yr Author 21 minutes ago, VisN said: What's the problem with the first 2? I'm glad you asked, because this is the part I know the least about. In two words: Clamp zones. PV modules are meant to be clamped around 25% from the top and bottom. A warranty claim might be denied if you install them any other way, but even on a technical level, a PV module is flexible and the wind actually flaps it like it might flap a tautly stretched blanket (just on a really small scale). So attaching them at the edges, like that, is actually one of the worst things you can do... depending of course on what the module maker says. This article has an example from Yingli that indicates the outer edges to be the least suitable place for mounting. Now these modules are not only mounted on the edges... they are mounted using a small extension so that the actual mounting point sits even further out. So if you think of my stretched blanket idea again, that small bracket is stressed all the time, and I can't see how well it is attached to the PV module (I hope it's by more than a few pop-rivets!). So maybe it is okay, maybe not... but I am pretty sure a warranty claim won't be honoured. Again, I'd love comments from others. I'm a little bit OCD whenit comes to PV nowadays, (I wasn't always, I became so over time), so of course I may be overly critical.
April 17, 20197 yr Author This is from a REC manual. Canadian solar has a whole page explaining how you should support the modules: From that you can see that bolting at the edges is okay, but then you must have a support in the middle.
April 17, 20197 yr 15 minutes ago, plonkster said: So attaching them at the edges, like that, is actually one of the worst things you can do just imagine what 1 meter of snow load will do to the panels 🤣. I am from northern Europe and will probably never be able to get rid of the anxiety what snow and ice can do to your structures. Although it is totally irrelevant here in Sunny SA.
April 17, 20197 yr Author 1 minute ago, Fuenkli said: Although it is totally irrelevant here in Sunny SA Right. Much of the support requirements have to do with downward force, eg snow as you mentioned. And the upward force seems to be unaffected by edge-mounting. So maybe this is indeed irrelevant in SA, and this way of mounting might be perfectly okay.... assuming the mounting brackets are firmly attached!
April 17, 20197 yr 7 minutes ago, plonkster said: and this way of mounting might be perfectly okay I don't think so. Your concerns are very valid. Even without snow (that was a joke I just could not resist of making) the stress on the panels and brackets over decades will be to high I think.
April 17, 20197 yr Author 25 minutes ago, Fuenkli said: I don't think so. Well, neither do I. But there are two ways to go about this. 1. I can act like some American electricians who do everything by code without understanding why or ever applying their mind to the matter, or... 2. I can apply my mind, but then I have to remember I'm a farmer-boy and not a structural engineer 🙂 By the first item, I reject the installation as it is not by code. The PV-module maker will reject warranty claims too, almost guaranteed. By the second item, I accept that it might be okay. But I suspect these guys aren't structural engineers either. It is done this way probably for cost reasons.
April 18, 20197 yr On 2019/04/17 at 8:47 AM, plonkster said: I'm glad you asked, because this is the part I know the least about. In two words: Clamp zones. PV modules are meant to be clamped around 25% from the top and bottom. A warranty claim might be denied if you install them any other way, but even on a technical level, a PV module is flexible and the wind actually flaps it like it might flap a tautly stretched blanket (just on a really small scale). So attaching them at the edges, like that, is actually one of the worst things you can do... depending of course on what the module maker says. This article has an example from Yingli that indicates the outer edges to be the least suitable place for mounting. Now these modules are not only mounted on the edges... they are mounted using a small extension so that the actual mounting point sits even further out. So if you think of my stretched blanket idea again, that small bracket is stressed all the time, and I can't see how well it is attached to the PV module (I hope it's by more than a few pop-rivets!). So maybe it is okay, maybe not... but I am pretty sure a warranty claim won't be honoured. Again, I'd love comments from others. I'm a little bit OCD whenit comes to PV nowadays, (I wasn't always, I became so over time), so of course I may be overly critical. You're right. The clamping zones is a big issue. Most big panel providers won't honor a claim if panels are installed this way. And I suspect heavy winds could tear, or lift, those panels off the roof. And, IMO, they're a bit close to the roof and might get hotter than they should. The battery cables should also not be open like that. Imagine a rat chows through it? SANS regulations stipulate that batteries need to be enclosed for safety reasons, which these aren't. And lead acid batteries in the bedroom will probably cause some health issues in the long run. Not to mention possible corrosion on some of their stuff as well. Edited April 18, 20197 yr by SilverNodashi
April 22, 20197 yr Author Aaaand here is another one... censored just a little to protect the guilty. Going through the photo gallery... there are a lot of well-done installs, just the occasional borderline one... AC and DC cabling in the same trunking... Clamp zones... Edited April 22, 20197 yr by plonkster
April 22, 20197 yr 59 minutes ago, plonkster said: AC and DC cabling in the same trunking... I know substations are excused from domestic wiring regulations, but out of necessity there are literally km's of mixed AC and DC cables mixed in cable trenches. Granted the majority of these cables are armored for mechanical integrity. However once the cables are terminated in the control cabinets, the wires share trunking all over the kip. It would be absolutely impractical cable management not to. I was speaking to a "design standards" guy last week, who told me that although it is frowned upon, if it is the last resort before having to pull in and entirely separate cable, they will even mix DC and AC cores within the same armored cable. It would be my job to investigate malfunctions of fairly sensitive protection relays in sub-stations, and as such I would have overseen the functionality of over a 100 kilometers of shared cable trenches, and hundreds of AC/DC control cabinets. I can't recall a single incident caused by AC to DC proximity at this level. The Telecoms crowd are a bit more fussy though, preferring to have dedicated clean and dirty supplies, but really think in your example above there will be zero issues. It is more important in a nett magnetic sense that the "there" and "back" current be it AC or DC travel in close proximity, sort of like the twisted pair principle.
April 22, 20197 yr Author 39 minutes ago, phil.g00 said: I can't recall a single incident caused by AC to DC proximity at this level. I know only one case of adjacent wiring causing a bad accident, and that was in aviation. I have done my fair share of trunk-sharing too... right now I have an ethernet cable and an AC cable sharing a piece of trunking to a router... 🙂
April 22, 20197 yr 1 hour ago, phil.g00 said: I know substations are excused from domestic wiring regulations, but out of necessity there are literally km's of mixed AC and DC cables mixed in cable trenches. Granted the majority of these cables are armored for mechanical integrity. However once the cables are terminated in the control cabinets, the wires share trunking all over the kip. It would be absolutely impractical cable management not to. I was speaking to a "design standards" guy last week, who told me that although it is frowned upon, if it is the last resort before having to pull in and entirely separate cable, they will even mix DC and AC cores within the same armored cable. It would be my job to investigate malfunctions of fairly sensitive protection relays in sub-stations, and as such I would have overseen the functionality of over a 100 kilometers of shared cable trenches, and hundreds of AC/DC control cabinets. I can't recall a single incident caused by AC to DC proximity at this level. The Telecoms crowd are a bit more fussy though, preferring to have dedicated clean and dirty supplies, but really think in your example above there will be zero issues. It is more important in a nett magnetic sense that the "there" and "back" current be it AC or DC travel in close proximity, sort of like the twisted pair principle. SANS still prohibit it, so there has to be a good reason for it. Probably cause domestic installations often use cheap(er), and thus less insulated, cables then in an industrial setting? With IT, we generally avoid mixing the two as the AC wires cause "cross talk", which in turn cause all sorts of havoc on network and telecom's wiring.
April 22, 20197 yr I use the pink Clipsal CBUS cable which has a much higher isolation rating than standard CAT5 and is allowed in a DB. Even then it's required to be separated as far as possible from the mains cables. I use it to connect all my low speed RS485 and LAN devices in my DB even though they are not really designed for LAN speeds but works perfectly fine.
April 22, 20197 yr 1 minute ago, SilverNodashi said: With IT, we generally avoid mixing the two as the AC wires cause "cross talk", which in turn cause all sorts of havoc on network and telecom's wiring This is clear, I did say the telecoms guys are persnickety. 1 minute ago, SilverNodashi said: Probably cause domestic installations often use cheap(er), and thus less insulated, cables then in an industrial setting? Nope, panel wire is panel wire. 7 minutes ago, SilverNodashi said: SANS still prohibit it, so there has to be a good reason for it. It has to be a safety concern not a functional one. Because if it was a functional concern we couldn't/wouldn't take the risk in substations. The difference is the people who are likely to be working on it, I think. In a substation, you won't get to fiddle without a higher level of authorized competencies. ( Electrician or engineer alike). Therefore we are excused some of the trivialities.
April 23, 20197 yr I dont think that electro magnetic interference is the main concern here. The problem comes in when you have cables with different insulation resistances in the same wireway. Running a router 12 V power cord up to a router/modem with a network cable is perfectly safe as CAT 5/ CAT6 cable is rated for 48V . But a network cable running with a 240 VAC cable poses a safety hazard As long as all the cables in the wireway has a minimum voltage rating higher than the highest voltage level in the wireway it should not be a safety issue. Edited April 23, 20197 yr by Jaws
April 23, 20197 yr 43 minutes ago, Jaws said: I dont think that electro magnetic interference is the main concern here. The problem comes in when you have cables with different insulation resistances in the same wireway. Running a router 12 V power cord up to a router/modem with a network cable is perfectly safe as CAT 5/ CAT6 cable is rated for 48V . But a network cable running with a 240 VAC cable poses a safety hazard As long as all the cables in the wireway has a minimum voltage rating higher than the highest voltage level in the wireway it should not be a safety issue. That is what I was referring to. I often see people skimp on the proper cable and buy the cheaper "alternative". Like speaker wire for solar panels. And @phil.g00 raise another valid point: the skill level of the installers on solar systems are on on the same level as those who are qualified to work on power stations.
April 23, 20197 yr 1 hour ago, SilverNodashi said: ... the skill level of the installers on solar systems are on on the same level as those who are qualified to work on power stations. I will agree that there ARE some super qualified people out there ... but the run of the mill installer advertising, I don't think so. 🙂 Have found some really dodgy ones out there, ones that don't even know the difference between grid tied and off-grid.
April 23, 20197 yr 5 minutes ago, The Terrible Triplett said: Have found some really dodgy ones out there, ones that don't even know the difference between grid tied and off-grid. I recon the guys laying down the law for SSEG in COT arent even sure about that 😂
April 23, 20197 yr 10 minutes ago, The Terrible Triplett said: I will agree that there ARE some super qualified people out there ... but the run of the mill installer advertising, I don't think so. 🙂 Have found some really dodgy ones out there, ones that don't even know the difference between grid tied and off-grid. Or the difference between AC and DC.
April 23, 20197 yr So you want to go into solar, go for a quick course, couple of thousand, and walla, there you go, you have a paper and can quote and install. Versus experienced sparkies that are AC and DC qualified, the ones most installers use to do their work for them. 🙂 Find those sparkies ... they do it cheaper than the "solar installer". As I've said before, sparkies will become the installers in the not so distant future.
April 23, 20197 yr I work a lot on HV and EHV equipment, no second chances there. “There are old mushroom hunters, and bold mushroom hunters, but no old bold mushroom hunters,” From the Mushroom Identification guide.
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